METHOD AND SYSTEM FOR ENERGY STORAGE CAPACITY ESTIMATION OF BATTER CELLS

• US 20150048801A1
• Filed: 11/06/2013
• Published: 02/19/2015
• Est. Priority Date: 08/19/2013
• Status: Active Grant

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Motorola Mobility LLC (Lenovo Group Ltd.)
• Inventors: Johnson, Robert M., Kessler, Kenneth L., Jakubowski, Richard
• Granted Patent: US 9,360,530 B2
• Time in Patent Office: Days
• US Class Current: 320/149
• CPC Class Codes: G01R 31/3842 combining voltage and current measurements
• CPC Class Codes: G06F 1/3212 Monitoring battery levels, e.g. power saving mode being initiated when battery voltage goes below a certain level
• CPC Class Codes: H02J 7/0048 Detection of remaining charge capacity or state of charge [SOC]
• CPC Class Codes: H02J 7/00719 in response to degree of gas development in the battery

Abstract

An apparatus (100) includes at least one electrochemical cell (106) and at least one pass element (104) serially coupled with the electrochemical cell. A control circuit (102) is operable to open the at least one pass element when a charger (105) or power supply (107) is connected to the electrochemical cell for at least a predetermined time and to measure an open circuit voltage of the at electrochemical cell to determine a state of charge. The control circuit can then close the pass element to charge the electrochemical cell, determine an amount of the charge, and store an estimated energy capacity of the electrochemical cell based upon the open circuit voltage and the amount.

Claims

1. A method of estimating cell capacity, comprising:

opening a circuit coupled serially between one or more cells of a battery and a charging terminal in response to detecting a charger coupled to the charging terminal and prior to the charger charging the one or more cells;

measuring, with a control circuit, an open circuit voltage of the one or more cells to determine a state of charge of the one or more cells;

after the measuring, closing the circuit to permit charging of the one or more cells by the charger;

determining an amount of the charging occurring after the closing; and

estimating an energy storage capacity of the one or more cells from the amount of the charging and the state of charge.

2. The method of claim 1, further comprising detecting whether an initial state of charge prior to the opening is within a predefined range.

3. The method of claim 2, the predefined range between about twenty percent and about sixty percent.

4. The method of claim 1, the opening occurring for at least a predetermined duration.

5. The method of claim 4, the predetermined duration at least two minutes.

6. The method of claim 1, further comprising detecting, with the control circuit, the charging nearing completion.

7. The method of claim 6, the detecting comprising detecting a charging current less than a predetermined threshold.

8. The method of claim 1, the measuring only occurring once between the opening and the estimating.

9. The method of claim 1, further comprising confirming the opening prior to the determining.

10. The method of claim 9, the confirming one of a measuring instantaneous current to the one or more cells or measuring an average current to the one or more cells.

11. The method of claim 1, further comprising powering an electronic device coupled to the battery while the opening occurs.

12. An apparatus, comprising:

at least one electrochemical cell;

at least one pass element serially coupled with the at least one electrochemical cell; and

a control circuit, operable with the at least one pass element to;

open the at least one pass element when a charger is connected to the at least one electrochemical cell for at least a predetermined time prior to charging;

measure an open circuit voltage of the at least one electrochemical cell after the predetermined time;

close the at least one pass element to charge the at least one electrochemical cell;

determine an amount of the charge; and

store an estimated energy capacity of the at least one electrochemical cell based upon the open circuit voltage and the amount.

13. The apparatus of claim 12, the at least one pass element comprising a transistor.

14. The apparatus of claim 12, the control circuit further to confirm the at least one electrochemical cell is within a predefined state of charge range before opening the at least one pass element.

15. The apparatus of claim 12, the control circuit to estimate a state of charge of the at least one electrochemical cell by referencing a look-up table stored in a memory operable with the control circuit.

16. A method of estimating cell capacity, comprising:

determining a charger connection to one or more electrochemical cells;

opening, with a control circuit, a circuit device disposed serially with the one or more electrochemical cells to preclude charging for a predetermined cell relaxation period;

after the predetermined cell relaxation period, identifying a state of charge of the one or more electrochemical cells;

closing, with the control circuit, the circuit device to charge the one or more electrochemical cells;

receiving, from a measurement circuit, an amount of charge occurring after the closing; and

estimating the cell capacity from the state of charge and the amount of charge.

17. The method of claim 16, the predetermined cell relaxation period sufficient for the estimating to be accurate within a predefined tolerance amount.

18. The method of claim 16, the estimating comprising dividing the amount of charge by a function of the state of charge.

19. The method of claim 16, further comprising confirming at least a predetermined duration since a previous estimating has passed prior to the opening.

20. The method of claim 16, further comprising precluding the estimating upon detecting interruption of the charger connection.